The present invention relates to a tester for use in testing coordinate measuring devices, the tester including a body element carrying a plurality of form-lockingly held balls for testing the X, Y and Z coordinates of the measuring device.
The accuracy of coordinate measuring devices can be determined and monitored by means of testers (see Technisches Messen [Technological Measuring], Volume 50, 1983, No. 5, pages 179-184) which permit the determination and examination of characteristic parameters.
A tester of this type is illustrated and described in paragraph 5 of VDI Berichte {VDI [Association of German Engineers] Reports] 529, published by VDI-Verlay GmbH, Dusseldorf, 1984, page 15. This tester is composed of a solid, plate-shaped body element equipped with a total of five balls which are connected to the plate-shaped body element in a form-locking manner. Four of these balls lie in one plane, and one ball is arranged 300 mm above that plane. The balls are arranged in a pattern at the corners of a square, and are disposed such that a base length exists between the balls at adjacent corners which is 600 mm. If such a tester is employed, the influence of the environmental conditions on the measuring results must be considered. A particularly critical influential parameter is considered to be the temperature, since temperature fluctuations have an influence on the geometry of the tester. Temperature gradients, for example, within the tester can practically not be determined at all nor compensated for by theoretical calculations.